Commingling

• Quantification and Commingling

  Mixed assemblages due to:

  •Mass fatality events

  •Mass graves

  •Ossuary
• Complexity

  •Small scale commingling vs large scale commingling – •Large and Complicated – World Trade Centre terrorist attacks on September the 11th (Mundorff, 2008)

  •Small scale – Helicopter crash Vietnam War – 2 individuals (Adams and Byrd, 2006)

  •Not always straightforward depending on set of circumstances

  •Complicated by taphonomic processes
• Recovery

  •Any association of remains starts with recovery

  •Careful recording at the scene, careful labelling

  •Extensive imaging and mapping

  •Patterns can assist with re-assembly

  •Associations should not be presumed

  •Recovery can cause commingling
• Sorting

  •Sorting will occur after recovery

  •Aim – sort, identify and rearticulate/reassociate

  •Identify commingling

  •Identify and remove non-human remains

  Requires anatomical/osteological knowledge
• Variation

  •Type of incident

  •Number of victims

  •Number of recovered remains

  •Degree of body fragmentation

  •Site/scene characteristics

  •Recovery processes
• Practical Steps

  Sort bone/tooth from other debris

  •Sort human from non-human remains

  •Inventory bones by type or side

  •Examine morphology

  •Age/sex/ethnicity be determined?

  •Consistency of size, length, robusticity, rugosity, joint surface congruence

  •Other information (bone colour, surface preservation, bone density, bone fragment fit).

  •Evidence of duplication
• Imaging

  Radiography

  •Body part reconciliation

  •Mass disaster investigations

  •Age and Sex determination
• Imaging

  Computed tomography (CT)

  •Body part reconciliation

  • 3D images

  •Identification

  • Facial approximation

  • Sex determination: images of sciatic notch, subpubic angle

  •Age determination: pubic symphysis, epiphyseal fusion

  •Assessment and interpretation of trauma

  •Intact charred and decomposing single individuals
• SWGANTH – resolving commingled human remains

  Visual pair matching -

  •Articulation

  •Process of elimination

  •Osteometric comparison

  •Taphonomy

  -Have to also add DNA as a method of reassociation

  -Discriminating power reduced as N increases

  -Consistency does not mean that they originated from the same person

  -Conversely, if two remains show incompatibility, they can be segregated with confidence.

  -Success of these methods is also dependent on levels of preservation.
• Visual Pair Matching

  •Bones sorted by element type, side and size (dimensions, gracile/robust), age (if appropriate.

  •Best with limited number of individuals who exhibit marked skeletal variation
• Articulation

  •Bone forms a congruent joint or juncture with another bone – articulation is an acceptable means for associating remains

  •Poor articulation can be basis for segregating remains

  •Problematic with fragmented or poor preservation
• Process of elimination

  •Useful in instances of small scale commingling

  •More problematic with larger number individuals

  Best to complete articulation and pair matching prior to process of elimination

  After this duplicated elements may remain that can be associated with individual through process of elimination
• Osteometric comparison

  •Uses statistical models to objectively compare size and shape relationships between elements

  •Removes subjective judgment calls – sound statistical basis

  •Extensive cortical erosion/fragmentation can cause a problem with applying these methods

  •Better at exclusion than association even when consistency found
• Taphonomy

  •Not a primary sorting technique

  •Can be very individuation

  •Traumatic disarticulation disperses portions of a single individual into very different contexts